Process of manufacturing electrical contact members



9, 1933. F. E. HENDERSON 1,907,931

PROCESS OF MANUFACTURING ELECTRICAL; CONTACT MEMBERS Filed NOV. 24 1930Patented May 9, 1933 UNITED STATES PATENT OFFICE FRED E. HENDERSON, OFRIVERSIDE, ILLINOIfi- ASSIGNOR T VTEQ'JXERN ELECTRIC COMPANY,INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK PROCESS O1MANUFACTURING ELECTRICAL CONTACT MEMBERS Application filed November 24,1930. Serial No. 497,761.

This invention relates to a process of manufacturing electrical contactmembers, and more particularly to a process of manufacturing bimetalliccontact elements.

It is the object of the present invention to provide an eflicientprocess of forming and attaching to electrical contact springs, b1-metallic contact elements utilizing a minimum 'quantity of contact metalwhile providing a maximum contacting surface.

In accordance with one embodiment, the invention contemplates forming awire of contact metal with a rounded upper surface, laterally extendingsubstantially flat projecting surfaces, and a small rounded lowersurface and combining the small rounded lower surface of the contactmetal with a flat, raised upper surface of a ribbon of base metal havingdownwardly extending rounded pro1ections extending longitudinally of thelower surface thereof. After combining the Wire of contact metal and theribbon of base metal a. welding current is passed through the contactmetal and base metal to fuse them at the line of contact therebetween,whereupon the contact metal is formed downwardly over an upwardlyextending surface of the base metal to provide an apron for preventingoxidation of the base metal due to arcing between the contacts-when inoperation. The composite strip thus formed may be cut to predeterminedlengths and positioned upon contact springs with the downwardlyextending proj ections of base metal engaging the upper surface of thespring and the electrodes of a welding circuit engaging substantiallyall of the exposed surfaces of the contact metal and an electrode ofopposite polarity engaging the undersurface of the contact spring toweld the composite element to the contact spring.

A better understanding of the invention may be had by referring to thefollowing detailed description of one embodiment thereof when consideredin conjunction withthe accompanying drawing, wherein Fig, 1 is asectional view through a wire of contact metal and a ribbon of basemetal positioned between welding electrodes prior to the posite strip ofcontact and base metal after the welding operation and prior to theforming of the contact metal to surround partially the base metal; i

Fig. 3 is a plan view of a composite strip of contact and base metalafter the contact metal has been formed to its ultimate shape;

Fig. 4 is a sectional view through a composite strip of baseand contactmetal after the contact metal has been formed to its ultimate shape, thestrip being shown positioned upon a contact spring with the position ofwelding electrodes used in'securing the contact element to the springshown in dot and dash lines, and

Fig. 5 is a perspective view of a contact spring with a compositebimetallic contact eleextending longitudinally thereof. After the wireof contact metal 6 has been formed, it Y may be combined with a strip 12of base metal such as nickel silver, pure nickel or other metals havinga high degree of resistance to corrosion. The strip of base metal isformed with an upwardly extending projection 14, the upper surface 13 ofwhich is fiat and which has surfaces 15 and 16 thereof inclineddownwardly from the surface 13 to meet laterally projecting flatportions 18 and 19, respectively, and with downwardly extending roundedridges 22 extending longitudinally thereof.

After the strips 6 and 12 of contact and base metal, respectively, havebeen formed to the hereinbefore described shape, they are combined asshown in 1 with the'downwardly extending portion 10 of the contact metalstrip 6, engaging the fiat upper surface 13 of the rojection 14 andwelding electrodes '24 and connected to a suitable welding circuit areplaced in engagement with the strips 6 and 12, respectively. The

electrode 24 is shaped at its lower end to conform to the curvature ofthe rounded surface 7 to provide a large area of contact between theelectrode and the contact metal, and the electrode25 is formed withslots 27 therein for receiving the downwardly extending rounded ridges22 of the base metal so that an intimate contact will be providedbetween the flat under surface of the base metal and the upper surfaceof the electrode to provide a comparatively large area of contacttherebetween. The electrodes may be of any known type but the preferredform of electrodes are circular constantly driven disk electrodes whichpermit the continuous welding of the compomte strip in any desired iththe base and contact metal thus combined and positioned between theelectrodes 24 and 25, the may be welded together by passing a wel trodesand through. the base and contact metal strip. A welding current, inpassing through the strip of'contact metal and the strip of base metal,will encounter its greatest resistance at the line of engagement of theridge 10 with the surface 13 of the base metal and due to the formationof the strip 6 only a small area of contact is provided between the baseand contact metals resulting'in a concentration of the'welding currentalong the line of contact. This concentration of the welding current andthe shape of the contact and base metal strips will cause fusion of thecontact metal and the base metal strip and will prevent the base metaland/or the contact metal from sticking to the welding electrodes or fromburning due to the fact that the relatively large area of base 'metaladjacent the line of contact withthe contact metal permi s of thedissipation of a comparatively great amount of heat, while thecomparatively small cross-sectional area of the contact metal adjacentthe line of contact with the base metal permits of very little heatdimipation in the contact metal, thereby resulting in the base metal andcontact metal strips reaching their respective 'fusing temperatures atapproximately the same time, providing in a strong welded union.Simultaneously with the application of the welding current to thestrips, pressure is exerted thereupon in the usual manner and the stripsare forced together ultimately assuming substantially the configurationshown in Fig. 2 wherein the numeral 29 indi cates 'the area of alloyedbase and contact metal after the fusing operation.

' A strip of base and contact metal joined together as shown in Fig. 2may then be mg current between the elecpressed or formed by suitableforming memoperation of the contacts in electrical appa- I ratus, fromstriking the base metal.

A composite strip of base and contact metal welded to ther and formed asshown in Figs. 3 an 4 ma then be cut to predetermined lengths a ong thelines 31 and 32 (Fig. 3) and placed upon the flat surfaces of contactsprings 34 in redetermined an lar position with the ridges 22 of thebase metal engagin the upper surface of the contact spring w ereu onelectrodes 36 and 37 as shown in dot an dash lines in Fig. 4 may beengaged wit-h the. upper surface of the composite contact element andthe under surface of the spring to transmit a welding current throughthe spring and contact member to weld the contact member onto thespring. The electrode 36 it willbe noted, engages substantially theentire surface of the contact strip, thereby providing a large area ofcontact between the electrode and the composite contact member. This,together with the line contacts between-the ridges 22 and the uppersurface of the spring 34, will result in the concentration of thewelding current alon a line of contact between the spring and 519 ridges22 to concentrate the weldin current at that point, thereby resulting inringing the base metal and the metal of the spring to a fusingtemperature at substantially the same time.

Although a specific embodiment of the iuvention has been described indetail hereinbefore, it will be understood that modifications andadaptations of the method described may be made without departing fromthe scope of the invention, which is to be limited only by the scope ofthe appended claims.

What is claimed is: I

1. The process of manufacturing bimetallic contact elements whichincludes forming a strip of contact metal with a rounded upper surface,a rounded lower surface and horizontally extending projecting portionsat each side thereof forming laterally projecting flat portions, forminga strip of base metal with an upwardly extending projection having aflat upper surface, combining the strip of contact metal arml the stripof base metal with the fiat upper surface of the base metal engaged bythe small rounded surface strip of contact surface a rounded lowersurface and hori-- accuser of the contact metal, and welding the contactmetal to the base metal.

2. The process of manufacturing bimetallic contact elements whichincludes forming a strip of contact metal with a rounded upper surface,a rounded lower surface and hori- Zontally extending projecting portionsat each side thereof forming laterally projecting flat portions, forminga strip of base metal with an upwardly extending projection having aflat upper surface, combining the strip of contact metal and the stripof base metal with the flat upper surface of the base metal engaged bythe small rounded surface of the contact metal, welding the contactmetal to the base metal, and forming the composite strip to its finalshape.

3. The process of manufacturing bimetallic contact elements whichincludes forming a strip of contact metal with a rounded upper surface,a rounded lower surface and horizontally extending projecting portionsat each side thereof forming laterally projecting flat portions, forminga strip of base metal with an upwardly extending projection having aflat upper surface, combining the strip of contact 7 base metal with theflat upper surface of the base metal engaged by the small roundedsurface of the contact metal, welding the con tact metal to the basemetal, and forming the projecting portions of the contact metal intooverlapping relation with the upwardly extending portion of the basemetal.

4. The process of manufacturing bimetallic contact elements whichincludes forming a metal with a rounded upper zontally extendingprojecting portions at each side thereof forming laterally projectingflat portions, forming a strip of base metal with an upwardly extendingprojection having a flat upper surface, combining the strip of contactmetal and the strip of base metal with the flat upper surface of thebase metal engaged by the small rounded surface of the contact metal,welding the contact metal to the base metal, and forming the compositestrip to its final shape to provide a flat upper surface and downwardlyinclined surfaces of contact metal covering the base metal.

5. The process of manufacturing bimetallic contact elements whichincludes forming a strip of contact metal with a rounded upper surface,a rounded lower surface and horizontally extending projecting portionsat each side'thereof forming laterally projecting fiat ortions, forminga strip of base metal with an upwardly extending projection having aflat upper surface, combining the strip of contact metal and the stripof base metal with the flat upper surface of the base metal engaged bythe small rounded surface of the contact metal, welding the contactmetal to the base metal, and forming the commetal and the strip of.

posite strip to its final shape, the exposed portions of the contactmetal being formed with a flat upper surface and downwardly inclinedside surfacesa I '6. The process of manufacturing bimetallic contactelements which includes forming a strip of contact metal with a roundedup per surface, horizontally extending projecting portions at each sidethereof forming laterally projecting fiat portions, forming a strip ofbase metal with an upwardly extending projection having a flat uppersurface and downwardly extending projections having rounded surfaces,combining the contact metal and the base metal with the small roundedportion of the contact-metal engaging the flat upper surface of the basemetal, welding the contact metal to the base metal, forming theprojecting portions of the contact metal into overlapping relation withthe upwardly extending surfaces of the base metal, and welding thecomposite strip of base and contact metal to a contact spring.

7. The process of manufacturing bimetallic contact elements whichincludes forming a strip of contact metal with a rounded upper surface,a rounded lower surface. and horizontally extending projecting portionsat each side thereof forming laterally projecting flat portions, forminga strip of base metal with an upwardly extending projection having aflat upper surface and downwardly extending projections having roundedsurfaces, combining the contact metal and the base metal with the smallrounded portion of the contact metal engaging the flat upper surface ofthe base metal, welding the contact metal to the base metal, forming theprojecting portions of the contact metal into overlapping relation withthe upwardly extending surfaces of the base metal, positioning thecomposite strip of'base and contact metal upon a contact spring with thedownwardly extending projections of the base metal in engagement withthecontact spring, and welding the composite strip to the contact spring.

8, lhe process of manufacturing bimetallic contact elements whichcomprises forming a strip of base metal with a projection on onesurface, forming a strip of contact metal with a projection on onesurface, combining a rounded lower surface, and

said strips with said projections in contact with each other,

to the base metal, and forming the contact metal over the projection onthe base metal.

In witness whereof, I hereunto subscribe FRED E. HENDERSON.

welding the contactmetal my name this 15th day of November A. 1).,

